The invention relates to the preservation of food products, in particular of bread products. In the case of such products a preserving gas, such as carbon dioxide, is added to the product in order to counteract spores of, for example, moulds or germs of bacteria. Oxidation of the product is also prevented. The shelf life of such food product increases as a result.
However, in the case of bread products the disadvantage is that the carbon dioxide has an adverse effect on the flavour. Efforts have been made to overcome this problem by using a mixture of nitrogen gas and carbon dioxide. However, since carbon dioxide dissolves quickly in the moisture present in a bread product, it is not the nitrogen gas, but the carbon dioxide which tends to go into the product, so that there is still an adverse effect on the flavour.
As a result of that effect, a certain separation therefore occurs in the pack, in the course of which the inert nitrogen gas which actually does not affect the flavour of the product disappears from the product. It is forced out by the carbon dioxide which initially was still outside the product in the pack.
Another disadvantage is that the carbon dioxide dissolves in the moisture of a product such as bread. As a result of this, the gas volume in the pack decreases, which in turn leads to shrinkage of pack with product. The product is in fact slightly compressed under the influence of atmospheric pressure. The saleability of the product is consequently reduced.